Hybrid forklifts including an engine and an electric motor as their drive sources and also including a battery or a battery pack to store electric power are excellent in energy efficiency.
In these hybrid forklifts, however, when the electric motor is frequently used, the batteries in the battery pack, such as lithium ion batteries, are frequently charged and discharged. Such frequent charge and discharge causes increase in the amounts of heat generated by the batteries, therefore increasing the temperatures of the batteries. This may possibly lead to the shortening of the batteries' lives. For this reason, in order to maintain the battery performance over a long period of time, the batteries need to be cooled.
One of the simplest configurations to cool the batteries may be a configuration shown in FIG. 9 in which a battery pack 3 is disposed in a cooling air flow passage 2 having a radiator 1 disposed therein to cool engine cooling water with cooling air, so that the batteries in the battery pack 3 are cooled with the cooling air sucked by a cooling fan 4 for the radiator.